1. Field of the Invention
The invention relates to operating devices and, more particularly, to an operating device for operating automation technology machinery.
2. Description of the Related Art
In commercially available operating devices for operating automation technology machinery, such as machine tools and/or production machines, in which the front panel consists of aluminum, sheet metal or plastic, the strip conductors of the membrane keyboard are led from the membrane keyboard to the electronics of the operating device arranged at the interior of the operating device by special flat cables also known as ribbon cables. For this purpose, a sizeable aperture is made in the front panel and the ribbon cables are led through the aperture. If necessary, the aperture is subsequently sealed, for example, by adhesive bonding. This connecting technique is known, and successfully proven, and is used in areas of the front panel of the operating device (in the case of front panels of aluminum, sheet metal or plastic), with which no production problems are encountered in this respect. For design reasons, the aperture for leading through the ribbon cables in the front panel lies under the membrane keyboard.
As previously stated, in the case of this conventional connecting technique, it is necessary to create a sizeable aperture in the front panel of the operating device to allow an electrical connection of the membrane keyboard and the electronics of the operating device. A comparable sizeable aperture in a glass panel is technically possible in principle, but very laborious to produce and involves a considerably increased risk of the panel breaking. This problem can be avoided by using plastic panels, since sizeable apertures can be made in them without any problem.
However, plastic panels have the fundamental disadvantage that they are less scratch-resistant in comparison to glass panels and have lower resistance to chemicals. Furthermore, with plastic panels there is the risk of discoloration of the material due to ambient influences, such as temperature, chemicals and harmful gases.
Furthermore, in the case of commercially available operating devices, membrane keyboards cannot be attached just anywhere on the front panel, because the aperture for the ribbon cable must not be externally visible, and consequently must, for example, disappear under a front surround. Consequently, the membrane keyboard can only be fitted at the periphery of the front panel. Moreover, the large aperture in the panel that is required for leading through the ribbon cable cannot be sealed well. Harmful gases and moisture can therefore get into the interior of the operating device and cause damage there to the electronics.